The present invention relates to a method for the mechanical compensation of moment sensitivity in shear beam transducers. The invention also relates to shear beam transducers which have been compensated in the mechanical manner disclosed herein.
The load sensitivity of a shear beam transducer should be ideally a constant value for a corresponding constant load regardless whether the load has been applied in the optimal loading point or off-center thereto. However, such constant relationship between the load and the sensitivity or output of the transducer is subject to certain influences which adversely affect the load sensitivity and thus the respective output which is indicated in millivolts per volt. For example, the constant relationship between the load and the output is assured only if the load is applied to the so-called optimal point of load application located on the optimal point of load application axis. If the actual point of load application shifts away from the optimal point, the output of the transducer may vary in an undesirable manner in one or the other direction. Thus, the output of the transducer may be larger or smaller than it should be for the given load value. This deviation is referred to in this disclosure as the moment sensitivity of the shear beam transducer. It is desirable to minimize this moment sensitivity and ideally reduce it to zero.
U.S. Pat. No. 3,949,603 discloses an electrical compensating method for minimizing this moment sensitivity of shear beam transducers. Such electrical compensation makes the transducer relatively insensitive to variations in the actual position of the point of load application relative to the optimal point of load application.
It has also been suggested in U.S. Pat. No. 3,960,228 to avoid off-center load applications by drilling a hole into the free end of the shear beam transducer to make sure that the applied load is directed in the optimal load measuring direction. However, from a practical point of view the precision required for such accurate load application exactly along the optimal load application axis, is too expensive and still does not assure that the desired result is always achieved.